Micro-fabrication by lithography using a photoresist composition has been carried out in manufacture of a semiconductor device. The micro-fabrication is a processing method in which a thin film of a photoresist composition is formed on a substrate to be processed such as a silicon wafer; the thin film is irradiated with active rays such as ultraviolet rays through a mask pattern in which a pattern of a semiconductor device is drawn and the irradiated thin film is developed; and the processed substrate such as a silicon wafer is processed by etching using the obtained photoresist pattern as a protection film.
In recent years, however, high integration of semiconductor devices has been progressed and wavelengths of active rays used tend to be shorter from KrF excimer laser (248 nm) to ArF excimer laser (193 nm). With this tendency, an effect of diffuse reflection of the active rays from a substrate and an effect of a standing wave have become large issues. Consequently, a method for providing an anti-reflective coating (Bottom Anti-Reflective Coating, BARC) between a photoresist and a processed substrate has been widely studied.
For example, a composition for forming a photosensitive resist underlayer film including a polymer having an acrylamide structure is disclosed (refer to Patent Document 1).
A composition for forming a resist underlayer film including a polymer having a structural unit of hydroxyacrylamide is disclosed (refer to Patent Document 2).
A composition for forming an anti-reflective coating including a polymer having a structural unit of a hydroxyalkylenemethacrylamide and a structural unit of an aromatic alkylene methacrylate is disclosed (refer to Patent Document 3).
In the future, when formation of a finer resist pattern is progressed, an issue of resolution and an issue of resist pattern collapse after development occur, and therefore, formation of a thinner resist will be desired. Consequently, it will be difficult to secure a sufficient resist pattern film thickness for substrate processing. As a result, a process that provides a function as a mask at the time of the substrate processing not only to the resist, but also to a resist underlayer film prepared between the resist and the processed substrate has become necessary. As the resist underlayer film used for the process described above, which is different from a conventional resist underlayer film having a property of a high etching rate (having fast etching rate), a resist underlayer film for lithography having a selectivity ratio of a dry etching rate close to that of the resist, a resist underlayer film for lithography having a selectivity ratio of the dry etching rate smaller than that of the resist, or a resist underlayer film for lithography having a selectivity ratio of the dry etching rate smaller than that of the semiconductor substrate has been required.